The present invention relates to a fin for a heat exchanger, and more particularly, to a fin for a heat exchanger for emitting heat from a thermal fluid flowing through a tube.
As shown in FIGS. 1, 2 and 3, a conventional heat exchanger has fins 1 and tubes 2. A plurality of slits 4 protruding up or down from fin 1 are formed to increase heat transfer with the air 3. The heat exchanger of FIG. 3 is disclosed from Korean Patent Application No. 88-14083.
Despite the demand for minimization and high performance of heat exchangers, air running speed between fins 1 is kept low to minimize noise. In the heat exchanger, the thermal resistance of the fin-surface gas is much higher than that of the internal gas. For this reason, the surface area of fin 1 is increased to reduce the difference between the thermal resistances of the external and internal gases. However, there is a limit to increasing the surface area of fin 1. At present, the thermal resistance of the fin surface far surpasses the internal thermal resistance of tube 2. Condensed water formed on the surface of the fins amplifies the thermal resistance of the external gas, decreasing the efficiency of the heat exchanger.
FIG. 4 shows a process of transferring heat of the heat exchanger from tube 2 to the air through fin 1. Heat is transmitted to fin 1 due to conduction from tube 2. By convection with air, heat is emitted from tube 2 and fin 1 to air, performing as a refrigeration load.
A heat exchanger's performance is determined by conduction and convection heat transfer. However, the conventional technology shown in FIG. 3 has the following disadvantages. Condensed water is hard to discharge due to the complicated shapes of the slits on the fin base. This decreases its heat transfer performance. In addition, a plurality of slits inhibit smooth air flow. Accordingly, the input loss at the front end of the heat exchanger is increased raising the fan load of the air conditioning unit.